Among the personal vehicles already sold on the market, those belonging to the self-balancing scooter family stand out.
These self-balancing scooters get their name from the fact that they use a gyroscopic stabilization system that makes it possible for their users to control the travel speed of the vehicle and its travel direction dynamically.
For the user, this dynamic control consists simply in moving its center of gravity toward the front to move the vehicle forward, to the rear to slow it down, and to the right or to the left when it is desired to head in one of its two directions.
Self-balancing scooters that are known and actually available on the market are sold under the brand names SEGMAY®, EWEE®, and ROBIN-M1®.
These three self-balancing scooters comprise two wheels that are motorized and mounted on either side of a platform on which the user stands upright and a driving column that extends from the platform and offers handlebars for the user at its upper end.
According to one drawback, the hands of the user are not free when he travels using one of these self-balancing scooters.
Actually, so as not to tip over and run the risk of falling violently on the ground, the user must necessarily grip the driving column by the handlebars.
In the best case, when using these self-balancing scooters, only the most expert users can hold them with one hand and perform an action or transport an object with the other hand.
Also, there are other personal vehicles that are similar to self-balancing scooters but that free the user's hands during travel.
For example, the TOYOTA® Company developed a self-balancing scooter under the name WINGLET® also taking the form of a platform with two motorized side wheels and on which the user stands upright.
However, unlike preceding self-balancing scooters, the driving column of the self-balancing scooter WINGLET® is replaced by two arms extending from the center of the platform and offering at their upper ends two supports for the user's legs, the two supports being located approximately at the height of the user's calves.
Thus, when using the self-balancing scooter WINGLET®, the user must clamp the two supports between his legs to stand upright balanced on the platform.
Although making it possible to free up the user's hands, the fact of having to clamp the supports between the legs can be tiring for the users, in particular on long trips.
Finally, in a general manner, and despite the performances of the new gyroscopic stabilization systems, all of the self-balancing scooters with side wheels similar to those that were just cited do not have absolute stability relative to pitching movements, i.e., rocking movements from front to back or from back to front, which can be caused by a driving error of the user or by an obstacle on the ground.
In addition, when the user transports an object by standing upright on such self-balancing scooters, his driving is disrupted by the weight of the object that he is transporting.
Actually, the transported object changes the center of gravity of the user, who should therefore adapt his driving to the weight of the object that he is transporting.
In parallel, the HONDA® Company developed a personal vehicle that bears the name of Uni-Cub® and that drives like a self-balancing scooter by moving its center of gravity.
However, unlike the vehicles described above, the Uni-Cub® comprises a saddle and side pedals making it possible for the user to ride in the seated position.
In addition, instead of two side wheels, the Uni-Cub® comprises a large center wheel whose tire tread consists of a multitude of transverse wheels arranged radially around the axis of rotation of the center wheel, as well as a transverse rear wheel whose axis of rotation is perpendicular to that of the center wheel and parallel to the front-rear direction of the vehicle.
If this arrangement of the wheels improves the stability of the vehicle relative to pitching movements, it reduces this stability relative to the rolling movements, i.e., the rocking movements from left to right and from right to left.
Finally, and although more comfortable, the seated position reduces the view and the access height of the user, which can turn out to be problematic for travel in the middle of a crowd, or in situations in which the user must stand to accomplish an action with his hands or to pick up an object.
Also, there are other personal vehicles that offer more stability thanks to a four-wheel design and that preserve the view and the access height of the user thanks to a half-seated half-standing driving position.
Such a vehicle is described in the application U.S. Pat. No. 6,845,829.
So as to free the user's hands, the personal vehicle described in this application U.S. Pat. No. 6,845,829 comprises rotating pedals that make it possible to guide the vehicle in a direction and to control its speed with the feet.
More specifically, two right and left pedals make it possible to control the speed of rotation of the shafts of two motors that independently drive the right and left rear wheels of the vehicle.
These two pedals are mounted to rotate on either side of the vehicle's chassis and around shafts perpendicular to the front-rear direction of the vehicle.
To control the vehicle in speed, the user makes the two pedals turn together with his feet toward the front or toward the rear, and to guide it in a direction, the user makes the two pedals turn differently from one another so that the two rear wheels have different rotating speeds, with the vehicle being directed from the side that is opposite to that of the wheel that turns the fastest.
Although relatively simple on the theoretical plane, the guiding of the vehicle described in the application U.S. Pat. No. 6,845,829 requires a certain dexterity and does not offer intuitive driving.
Actually, few people are naturally accustomed to guiding a vehicle in a direction by actuating two pedals or two levers simultaneously but in a different manner.
According to another drawback, the pedals of the vehicle described in the application U.S. Pat. No. 6,845,829 are located under the vehicle seat and in the vertical axis of this seat, supporting plates being provided at the front of the vehicle's chassis and at mid-height between the pedals and the seat for the user's knees.
This positioning of the pedals imparts a driving position that promotes the tilting of the top of the user's body toward the front, in particular during a deceleration of the vehicle.
Also, to remedy this drawback, the document U.S. Pat. No. 6,845,829 provides a railing that surrounds the user's waist.
However, this railing turns out to be uncomfortable, and it prevents the user from quickly getting on and off the vehicle, which can be problematic within the framework of professional use.